Well...personally I'd go with the 87' then, even though it is higher mileage. a: The price is right. b: a gummy area is always better than a nice clean oil leak (less leakage volume/rate) c: back to the original idea of if your willing to live with it or fix it. So with that in mind.....the 87' sounds like the one...assuming the rest of the car is good, and your only concerned with the oil issues.
88' 190E 2.3
79' 280CE (Sold)
68' VW Bug (what the hell was I thinking!)
99' HD FLSTF